WO2024161255A1

WO2024161255A1 - Endoprosthesis and endoprosthesis system

Info

Publication number: WO2024161255A1
Application number: PCT/IB2024/050718
Authority: WO
Inventors: Gabriel Tschupp; Stefan Saladin
Original assignee: Mathys AG Bettlach
Current assignee: Synthes Bettlach GmbH
Priority date: 2023-01-31
Filing date: 2024-01-25
Publication date: 2024-08-08
Anticipated expiration: 2025-07-31
Also published as: DE102023116397A1; DE102023116386A1; DE202023100431U1; DE102023116366A1; DE102023116374A1

Abstract

In some embodiments, apparatuses and methods are provided herein useful to an endoprosthesis. In some embodiments, an at least partial endoprosthesis is disclosed wherein the at least partial endoprosthesis is designed such that the sagittal cut, which is required in particular for corresponding implantation, deviates decentrally in the anterior region, and/or wherein an anterior region of the at least partial endoprosthesis, which in particular faces the anterior region of the corresponding tibia after insertion of the at least partial endoprosthesis into the human body, has an inclined surface.

Description

ENDOPROSTHESIS ANw I. MJ JI ROSTI I ESIS SYSTEM

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to German Utility Model Application No. 20 2023 100 431.8 filed on January 31, 2023, which is hereby incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

[0002] The disclosure relates to an endoprosthesis and an endoprosthesis system for an at least partial joint replacement having improved properties.

BACKGROUND

[0003] Due to an increasing life expectancy of humans and the associated increased likelihood or necessity of replacing at least a portion of at least one joint by a corresponding implant at least once in the course of life, the demand for joint replacement having improved properties is increasing, in particular in order to ensure the highest possible quality of life for the respective patients, even after corresponding implantation.

PROBLEM AND SOLUTION

[0004] Accordingly, the problem addressed by the disclosure is that of providing an at least partial or complete joint replacement having improved properties.

[0005] The problem is solved by the features of the independent claims. The dependent claims contain advantageous developments.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0006] According to a first aspect of the disclosure, an at least partial endoprosthesis is created, in particular for the human knee. In this case, the at least partial endoprosthesis is designed in such a way that the sagittal cut, which is required in particular for corresponding implantation, deviates decentrally in the anterior region. Additionally or alternatively, an anterior region of the at least partial endoprosthesis, which faces the anterior region of the corresponding tibia after insertion of the at least partial endoprosthesis into the human body, has an inclined surface. Advantageously, the properties of the joint replacement are improved for example in that a corresponding implantation is easier to carry out. It should be noted that the at least partial endoprosthesis can also be a complete or total endoprosthesis. In addition, it should be noted that the sagittal cut does not necessarily have to be a cut which, for example, is carried out using a laser; the corresponding region can aiso oe removed by means of a cutter, for example. It could accordingly also be said that the sagittal cut surface or the sagittal surface deviates decentrally in the anterior region. Preferably, the sagittal cut or the sagittal (cut) surface has a curved or rounded or round basic form.

[0007] According to a first preferred embodiment of the first aspect of the disclosure, the inclination of the inclined surface is between 20 degrees and 70 degrees, preferably between 25 degrees and 65 degrees, particularly preferably between 30 degrees and 60 degrees, very particularly preferably between 35 degrees and 55 degrees, in particular with respect to the tibia. Advantageously, the corresponding implantation can thus be further simplified, for example.

[0008] According to a second preferred embodiment of the first aspect of the disclosure, the at least partial endoprosthesis has a gradual transition, in particular between a sagittal surface and a horizontal surface of the at least partial endoprosthesis. Advantageously, the risk of a tibial plateau fracture can thus be significantly reduced for example, in particular since the mechanical load in this region is correspondingly reduced.

[0009] According to a further preferred embodiment of the first aspect of the disclosure, the gradual transition has a radius. Advantageously, for example the risk of a tibial plateau fracture can thus be further reduced.

[0010] According to a further preferred embodiment of the first aspect of the disclosure, the at least partial endoprosthesis has or is a bi-compartmental endoprosthesis. Advantageously, for example the remaining bone structure in the region of the tibial attachment of the anterior cruciate ligament is thus larger.

[0011] According to a second aspect of the disclosure, an endoprosthesis system is created, the system having at least two at least partial endoprostheses according to the first aspect of the disclosure or a preferred embodiment thereof. Advantageously, the properties of the joint replacement are improved for example in that a corresponding implantation is easier to carry out.

[0012] According to a first preferred embodiment of the second aspect of the disclosure, the system is used in connection with a bicondylar femur. Advantageously, for example a significant weakening of the bone around the tibial attachment of the anterior cruciate ligament can thus be avoided.

[0013] According to a third aspect of the disclosure, an endoprosthesis is created, at least a portion of a surface of the endoprosthesis facing the corresponding bone and/or joint part having a macrostructure for ensuring the primary stability of the endoprosthesis. Advantageously, the properties of the joint replacement are improved for example in that elements such as a peg and/or fin can be dispensed with, at a constant stability. Dispensing these elements also facilitates later amendment of the endoprosthesis and also leads to a reduction in the corresponding loss of bone.

[0014] According to a first preferred embodiment of the third aspect of the disclosure, the surface facing the corresponding bone and/or joint part has the macrostructure completely or extensively. Advantageously, for example the primary stability can thus be further increased. A further advantage is that the strength is generated in particular by the bone, and very thin and flexible endoprostheses are thus possible.

[0015] According to a second preferred embodiment of the third aspect of the disclosure, the macrostructure has honeycomb structures, in particular honeycomb-shaped ribs, and/or waveshaped structures, in particular wave-shaped ribs, and/or zigzag structures, in particular zigzag ribs, and/or tire tread-like structures, in particular tire tread-like ribs. Advantageously, for example shear forces can thus be absorbed in all directions.

[0016] According to a further preferred embodiment of the third aspect of the disclosure, the macrostructure has a plurality of spines and/or pins and/or spikes. By means of this plurality, for example a connection can advantageously be created which substantially corresponds to a full-surface connection.

[0017] According to a further preferred embodiment of the third aspect of the disclosure, at least some, preferably each, of the spines and/or pins and/or spikes has a length between 4 mm and 8 mm, preferably between 5 mm and 7 mm, particularly preferably between 5.5 mm and 6.5 mm, very particularly preferably approximately 6 mm. Advantageously, for example the primary stability can thus be further increased.

[0018] According to a further preferred embodiment of the third aspect of the disclosure, at least some, preferably each, of the spines and/or pins and/or spikes has a diameter between 0.5 mm and 2.5 mm, preferably between 1 mm and 2 mm, particularly preferably between 1.3 mm and 1.7 mm, very particularly preferably approximately 1.5 mm. Advantageously, for example the primary stability can thus be further increased.

[0019] According to a further preferred embodiment of the third aspect of the disclosure, the corresponding structures of the macrostructure are designed to be larger and/or deeper in regions in which greater loads and/or a lower bone quality are to be expected with respect to the corresponding bone and/or joint part. Advantageously, for example the primary stability can thus be further increased. [0020] According to a further preferred emoouimem of the third aspect of the disclosure, the endoprosthesis has or consists of a flexible material, preferably flexible thin material, particularly preferably polyethylene, very particularly preferably polyethylene having a thickness of between 1.5 mm and 2.5 mm, and/or biomaterial. For example, this results in the following advantages: Especially in the case of endoprostheses for early treatment of local damage, it is important that these can later be amended using a conventional endoprosthesis. For this purpose, the tissue damage should be kept as little as possible, which is made possible in this way. Furthermore, it is advantageously possible to remove predominantly or exclusively the corresponding cartilage and to keep the bone as far as possible. For this purpose, for example a laser can be used, which is in particular designed to detect whether it is removing bone or cartilage. In addition, the laser can be used to provide the corresponding bone with structures which preferably interact with the macrostructure.

[0021] According to a further preferred embodiment of the third aspect of the disclosure, the endoprosthesis has or consists of plastics material, in particular polyether ether ketone (PEEK) and/or polyaryletherketone (PAEK) and/or polyethylene (PE) and/or ultra-high molecular weight polyethylene (UHMWPE) and/or UHMWPE mixed with Vitamin E and/or hydrogel, and/or artificial cartilage and/or human cartilage. Advantageously, for example particularly good compatibility of the endoprosthesis can thus be ensured.

[0022] According to a fourth aspect of the disclosure, an intraoperatively adaptable endoprosthesis is created. In this case, the intraoperatively adaptable endoprosthesis has a basic form, the basic form being adapted intraoperatively on the basis of shape data according to the anatomical conditions of the respective patient. Advantageously, the properties of the joint replacement are improved for example in that the shape or basic form of the endoprosthesis is optimally adaptable to the situation to be encountered intraoperatively, and no patient-specific endoprostheses have to be prefabricated.

[0023] According to a first preferred embodiment of the fourth aspect of the disclosure, the shape data are obtained intraoperatively in particular by means of computer tomography and/or magnetic resonance tomography and/or endoscopy and/or sonography and/or 3D scans, preferably light-based and/or laser-based 3D scans. Advantageously, for example there is no need to provide apparatuses which serve specifically for the purpose of obtaining shape data, as a result of which the corresponding costs can be kept low.

[0024] According to a second preferred embodiment of the fourth aspect of the disclosure, the basic form is adapted by milling, in particular CNC milling, and/or laser cutting and/or water jet cutting. Advantageously, for example a simple anu efficient adaptation of the basic form can thus be ensured.

[0025] According to a further preferred embodiment of the fourth aspect of the disclosure, the intraoperatively adaptable endoprosthesis and/or the basic form has or consists of artificial cartilage and/or human cartilage. Advantageously, for example particularly good compatibility of the endoprosthesis can thus be ensured.

[0026] According to a fifth aspect of the disclosure, an endoprosthesis is created, the endoprosthesis having at least one structure for ensuring the primary stability of the endoprosthesis, the at least one structure having or consisting, at least in part, of a material that can be resorbed by the human body. Advantageously, the properties of the joint replacement are improved for example in that the corresponding loss of bone during an amendment is minimized.

[0027] According to a first preferred embodiment of the fifth aspect of the disclosure, the at least one structure entirely has the material that can be resorbed by the human body, or consists of said material. Advantageously, for example the corresponding loss of bone during an amendment can thus be reduced even further.

[0028] According to a second preferred embodiment of the fifth aspect of the disclosure, the at least one structure has at least one anchoring pin, in particular at least one peg, and/or at least one fin. Advantageously, for example a correspondingly greater design scope can thus be achieved, in particular since a possible adaptation does not have to be taken into account in the shape of the at least one structure or corresponding macrostructures.

[0029] According to a further preferred embodiment of the fifth aspect of the disclosure, the material that can be resorbed by the human body has magnesium and/or polylactide (PLLA) and/or poly(lactic-co-glycolic acid) (PLGA) or is magnesium and/or PLLA and/or PLGA. Advantageously, for example a corresponding resorption can thus be ensured in an efficient manner.

[0030] According to a further preferred embodiment of the fifth aspect of the disclosure, at least a portion of a surface facing the corresponding bone and/or joint part, preferably the surface facing the corresponding bone and/or joint part, of the endoprosthesis, is designed to enable the corresponding bone and/or joint part to grow. Advantageously, the growth is facilitated by the at least one structure.

[0031] According to a further preferred embodiment of the fifth aspect of the disclosure, at least the part of the surface facing the corresponding bone and/or joint part, preferably the surface facing the corresponding bone and/or joint part, of the endoprosthesis, has titanium and/or titanium particles. Advantageously, ror example the growth can thus be yet further facilitated. It should be noted that preferably those regions which are not resorbable have the titanium and/or the titanium particles.

[0032] According to a further preferred embodiment of the fifth aspect of the disclosure, the endoprosthesis has an endoprosthesis according to the third aspect of the disclosure or a preferred embodiment thereof, or is such an endoprosthesis. Advantageously, for example not only can the corresponding bone loss during adaptation thus be minimized, but rather a particularly high primary stability can also be ensured.

[0033] According to a further preferred embodiment of the fifth aspect of the disclosure, the at least one structure has the macrostructure or is such a macrostructure.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0034] In the following, a detailed description, by way of example, of some embodiments of the disclosure is given, with reference to the figures of the drawing, in the figures:

[0035] Fig. 1 A shows a first surgical cut within the scope of a partial removal of a tibia;

[0036] Fig. IB shows a second surgical cut within the scope of a partial removal of a tibia;

[0037] Fig. 2A shows a view from above, by way of example, of the right tibia of a knee joint, having an indicated surgical cutting guide within the meaning of the disclosure and according to a traditional cutting guide;

[0038] Fig. 2B shows the exemplary view according to Fig. 2A having an indicated surgical cutting guide within the meaning of the disclosure and having markings for correspondingly sagittal and transverse sectional views according to Fig. 2C;

[0039] Fig. 2C shows sagittal and transverse sectional views, by way of example, with respect to the markings of Fig. 2B;

[0040] Fig. 3 shows honeycomb-shaped ribs by way of example, in particular for the extensive anchoring of the corresponding implant within the meaning of the disclosure;

[0041] Fig. 4 shows macrostructures, by way of example, depending on load and bone quality, in the context of the extensive anchoring within the meaning of the disclosure; and

[0042] Fig. 5 shows an embodiment, by way of example, of an implant, in particular of a tibia implant, having resorbable pegs within the meaning of the disclosure.

[0043] For later explanation of the first aspect and of the second aspect of the disclosure, it should first be noted that the human knee joint 10, by way of example, which can be seen in Fig. lAand IB, consists of three partial joints, namely femur-patella, medial condyle-tibia, and lateral condyle-tibia. [0044] In the case of a partial knee prosthesis, omy one partial joint is replaced. In the case of the medial and lateral partial prosthesis, a portion of the tibia is removed using two straight cuts. These two surgical cuts according to a traditional cutting guide, in the case of partial knee joint replacement, are illustrated by Fig. 1A and IB. For the sake of completeness, it should also be noted that methods also exist within the scope of which the bones are removed using a bone cutter. However, the central vertical cut according to Fig. 1 A is common to all known methods. The removed bone is then filled with an implant. It should also be noted that the central vertical cut is not necessarily to be designed as a cut, for example with the aid of a saw. This can, for example, also be carried out using a bone cutter, the corresponding sagittal surface - analogously to the cut - remaining straight.

[0045] The straight vertical cut according to Fig. 1 A weakens the region in which the anterior cruciate ligament attaches to the tibia. In particular if both the medial and lateral condyles are to be replaced, there is a risk that the enthesis may break. Furthermore, the anterior region of the tibia is not in contact with the femur. The risk of a corresponding tibial fracture is not insignificant.

[0046] Both the first aspect and the second aspect of the disclosure are now explained below with reference to Fig. 2Ato 2C.

[0047] Fig. 2A is a view from above, by way of example, of the right tibia of a knee joint having an indicated surgical cutting guide 21 within the meaning of the disclosure and according to the traditional cutting guide 22, while Fig. 2B is the view by way of example according to Fig. 2A having an indicated surgical cutting guide 21 within the meaning of the disclosure and having markings 23a, 24a for correspondingly sagittal and transverse sectional views 23b, 24b according to Fig. 2C.

[0048] With regard to the sectional view 24b, it should also be noted that, in this case, the correspondingly anterior (A) and the corresponding posterior (P) region are marked in each case.

[0049] With regard to Fig. 2A and 2B, it should also be noted that, in particular for better orientation, not only is the correspondingly anterior region marked by the reference sign 31, but rather the following components of the tibia, shown by way of example, are also illustrated in each case: Articular cartilage on the lateral tibial condyle 25, lateral meniscus 26, rear cruciate ligament 27, medial meniscus 28, articular cartilage on the medial tibial condyle 29, front cruciate ligament 30.

[0050] Furthermore, it should be noted that, in particular according to the surgical cutting guide 21 within the meaning of the disclosure, it can be particularly advantageous if the at least partial endoprosthesis for the human knee is designeu in such a way that the sagittal cut, which is required in particular for corresponding implantation, deviates decentrally in the anterior region.

[0051] In this context, the corresponding cut within the meaning of the disclosure is preferably carried out using a cutter and/or laser, particularly preferably using a guided cutter and/or guided laser, very particularly preferably using a cutter guided by means of robotics and/or a laser guided by means of robotics.

[0052] In particular in order to be able to implant the at least partial endoprosthesis more easily, the anterior region of the endoprosthesis preferably has an oblique surface, for example at 30 degrees to 60 degrees. Accordingly, the corresponding bone also preferably has such an oblique or inclined surface.

[0053] Furthermore, it is important not to overlook the fact that, in particular in the case of partial knee joints, there is a risk of a tibial plateau fracture. In particular against this background, it can be particularly advantageous if the transition between a correspondingly sagittal and correspondingly horizontal surface of the at least partial endoprosthesis is gradual, for example over a radius. The aforementioned risk can thus be minimized, in particular because the gradual transition results in a reduction in the mechanical load in the corresponding region.

[0054] As already essentially stated above, the at least partial endoprosthesis can advantageously be designed such that a corresponding implantation requires a curved and/or gradual bone preparation. This can also result in a significant advantage in the case of bicompartmental implants: The remaining bone structure in the region of the front cruciate ligament attachment is larger than for example in the case of previously known endoprostheses. Furthermore, the corresponding bone preparation in the case of the operative cut, which is required by the at least partial endoprosthesis within the meaning of the disclosure, has less mechanical load in this context too, which reduces the risk of rupture of the cruciate ligament attachment.

[0055] In particular within the scope of the second aspect of the disclosure, it should be noted that, for artificial bicondylar knee joints, i.e., artificial knee joints which replace both the medial and lateral sides, typically the entire tibial plateau has to be resected, and the anterior cruciate ligament must be removed accordingly. Even if the anterior cruciate ligament should not be removed, the corresponding cutting guide significantly weakens the bone around the anterior cruciate ligament. Such a weakening of the bone around the anterior cruciate ligament thus cannot be avoided in connection with all previously known endoprostheses. This results in particular in an increased risk of a fracture in rne region of the attachment of the anterior cruciate ligament.

[0056] In particular, in order to significantly reduce this risk, it can be particularly advantageous, preferably within the meaning of the second aspect of the disclosure, for the corresponding tibia to be replaced by two tibias according to the disclosure or two at least partial endoprostheses within the meaning of the first aspect of the disclosure, when a bicondylar femur is used.

[0057] For the later explanation of the third aspect of the disclosure, reference is first made to the following background: If a joint replacement or an implant is to be connected to the bone, there are in principle two options: The implant can be fixed to the bone by means of polymethylmethacrylate cement (PMMA cement), or said implant has a suitable surface, for example structured titanium surfaces, onto which the bone can grow.

[0058] In order to enable the bone to grow in or onto the implant, the implant may move relative to the bone only within narrow limits. This limitation of the micromovement between the implant and bone is known as primary stability. This can be achieved, for example, by form and press fitting or elements, for example screws, between the bone and implant.

[0059] The press fit can be formed either locally or via the implant basic form. An example of the local press fit is a peg. This can fix the implant at this local point by means of a hole in the bone that is purposely smaller with respect to the larger diameter of the peg.

[0060] Another possibility is that two opposing surfaces of an implant result in a press fit. In this case, the bone is prepared with oversize relative to the implant surfaces. Depending on the implant, these surfaces are at different positions. For example, in the case of a corresponding femur, in particular a bocondylar femur, a press fit is established between the anterior and posterior implant surfaces. Thus, the fixing exists only between the corresponding surfaces.

[0061] Other implant shapes, for example in the context of a tibia, do not enable a press fit between two surfaces, due to their required geometry. In the case of a hip stone, however, the implant shape can be used, for example, as a conical press fit with respect to the bone.

[0062] The third aspect of the disclosure is now explained below with reference to Fig. 3 and 4. Within the meaning of the third aspect of the disclosure, in particular an efficient possibility for achieving the primary stability for endoprostheses is provided. The endoprosthesis according to the third aspect of the disclosure makes it possible in particular for the endoprosthesis to connect to the bone extensively, in a form-fitting manner, preferably over the entire surface of the endoprosthesis. [0063] Advantageously, the third aspect oi rne uisciosure is independent of the corresponding shape of the endoprosthesis. For example, this can relate to the anterior and/or posterior surface of a femur endoprosthesis, or also other endoprostheses. In addition, there is an independence of point connections such as a peg, fin, or the like.

[0064] The corresponding anchoring of the endoprosthesis advantageously results via a macrostructured surface of the endoprosthesis. It should be noted that the corresponding bone may also be provided with a macrostructure which preferably generates a very large number of anchoring points.

[0065] The macro-structured surface or macrostructure used in particular for anchoring can preferably have honeycomb-shaped ribs 40, according to Fig. 3. Advantageously, this shape results in a corresponding shear force being able to be absorbed in all directions, which is illustrated by way of example by the reference signs 41, 42, 43 in Fig. 3.

[0066] An additional or alternative possibility consists of many individual points which lie so close to one another that a quasi full-surface connection also results. These individual points can be many small spikes, for example approximately 1.5 mm in diameter and/or approximately 6 mm in height or length.

[0067] It should also be noted that the load on the bone can be different over the course of the corresponding surface or of the corresponding bone interface. The expected bone stiffness can also vary on the corresponding bone interface. This situation is illustrated with the aid of Fig.

4. Here, the curve having reference sign 51 illustrates the corresponding bone density, while the curve having reference sign 52 relates to the corresponding load.

[0068] This load gradient and the bone quality can be incorporated into the design of the structures, which can be seen from the macrostructure or the anchoring structures 53 according to Fig. 4. Thus, preferably at locations at which large loads are expected and/or the bone quality is less good, the structures can be designed to be larger and/or deeper than in regions having small or smaller loads and good or better bone quality. In addition, both the corresponding endoprosthesis 54 and the corresponding bone 55 are shown in Fig. 4.

[0069] As already essentially indicated above, the endoprosthesis, within the meaning of the third aspect of the disclosure, can advantageously be connected to the bone on the entire surface. As a result, elements such as a peg and/or fin can be dispensed with, at constant stability. Dispensing with these elements facilitates later amendment of the implant. In the case of such an amendment, the bone loss is also reduced.

[0070] An implant which is connected to the bone only at individual regions must typically be inherently rigid. In particular, due to the connection over the entire surface, the endoprosthesis can be manufactured, within the meaning or me rniru aspect of the disclosure, from a flexible material, for example plastics material such as PE and/or UHMWPE and/or hydrogel and/or artificial cartilage. The use of biomaterials which are structured in a targeted manner is also conceivable.

[0071] Afurther advantage is in particular that, on account of the insertion of an endoprosthesis within the meaning of the third aspect of the disclosure, the strength is generated substantially by the corresponding bone, and very thin and flexible endoprostheses are thus possible. Especially in the case of endoprostheses for early treatment of local damage, it is important that these can later be amended using a conventional endoprosthesis. For this purpose, the tissue damage must be kept as low as possible.

[0072] Furthermore, it should be noted that, within the meaning of the third aspect of the disclosure, the endoprosthesis also has or can consist of human cartilage. In this context, for example a piece of cartilage at a location of the human body at which it is in particular not required can preferably be removed by means of a laser, and, in particular after the cartilage has been provided with the macrostructure, can preferably be inserted with the aid of a laser at the correspondingly desired location.

[0073] For the later explanation of the fourth aspect of the disclosure, it should first be noted that essentially one of the success factors of endoprostheses is that the respective endoprosthesis fits as precisely as possible to the patient-specific shape. In order to achieve this, either the correct size can be selected from an existing, discrete product portfolio of endoprostheses, or a patient-specific endoprosthesis can be manufactured on the basis of preoperative computer tomography or magnetic resonance tomography data.

[0074] An existing portfolio is usually designed for an average shape. If the patient deviates from this shape, however, the implant will not perfectly fit the anatomical conditions. If the shape is designed on the basis of preoperative computer tomography or magnetic resonance tomography data and is produced before the operation, the shape thus cannot cater to intraoperative deviations. Furthermore, depending on the production and logistics time, spontaneous surgery may not be possible.

[0075] The fourth aspect of the disclosure provides that the endoprosthesis is adapted intraoperatively to the anatomy in a defined region. For this purpose, the optimal shape of the joint replacement or the endoprosthesis is determined, in particular intraoperatively due to the circumstances, for example by means of a laser scanner or the like. The joint replacement or the endoprosthesis is then preferably cut to size accordingly. The cutting to size can take place intraoperatively by means of different tecnnoiogies, for example CNC milling, laser cutting, waterjet cutting.

[0076] Furthermore, the intraoperatively adjustable endoprosthesis can be designed to replace exclusively damaged cartilage. Furthermore, the intraoperatively adjustable endoprosthesis can also be made of a piece of artificial or human cartilage.

[0077] Furthermore, it should be noted that, in particular in the case of minimally invasive technologies in which only the damaged cartilage is replaced, the corresponding form of damage is to be determined very differently and only intraoperatively. An embodiment of the fourth aspect of the disclosure provides that the corresponding form of damage is determined intraoperatively, and then serves as a shape basis for the intraoperative cutting to size of the endoprosthesis.

[0078] It is also possible for the damaged cartilage to be marked and subsequently to be removed, at least in part automatically. An essential advantage of the fourth aspect of the disclosure is that the endoprosthesis or its shape is optimally adapted to the situation that exists intraoperatively, and no patient-specific endoprostheses have to be prefabricated.

[0079] For the later explanation of the fifth aspect of the disclosure, reference is first made to the following background: In order to connect a joint replacement or an implant to the bone, there are essentially two options: The joint replacement or the implant can be fixed to the bone by means of polymethylmethacrylate cement (PMMA cement), or it has a suitable surface onto which the bone can grow, for example structured titanium surfaces.

[0080] In order to enable the bone to grow in or onto the implant, the implant or the endoprosthesis may move relative to the bone only within narrow limits. This limitation of the micromovement between the implant and bone is known as primary stability. This can be achieved, for example, by form and press fitting or elements, for example screws, between the bone and implant.

[0081] In the case of a later amendment, it would be advantageous if the least possible bone is lost. Although pegs and fins for example bring about the required primary stability during implantation, they cause significant bone damage during explantation.

[0082] The fifth aspect of the disclosure is now explained below with reference to Fig. 5. According to this aspect of the disclosure, the corresponding bone interface of an endoprosthesis, for example a joint endoprosthesis, can consist of two parts. The surface facing the corresponding bone and/or joint part preferably consists of a material, for example titanium, onto which the bone can grow. [0083] Structures, for example a peg, fin, or rne ime, provide the desired stability at the start, especially by a press fit, so that the surface facing the corresponding bone and/or joint part can grow.

[0084] These structures preferably consist at least in part of a material, for example magnesium, which can be rebsorbed by the human body. The material is advantageously to be designed such that for example the pegs or corresponding other structures still provide a sufficient press fit during the growth, but are almost completely or completely decomposed at the time of explantation.

[0085] The above-mentioned Fig. 5 illustrates an embodiment, by way of example, of an endoprosthesis 61, in particular a tibia endoprosthesis, having resorbable anchoring structures 62, in particular having resorbable pegs. In addition, the corresponding bone 63 is shown in Fig. 5. The macrostructure shown accordingly in Fig. 5 can also be based on or at least partially consist of the macrostructure according to the third aspect of the disclosure or of a preferred embodiment thereof, or can be such a macrostructure.

[0086] The corresponding bone loss during an amendment is advantageously minimized by the fifth aspect of the disclosure. A further advantage is also obtained: In particular, since a possible adaptation does not have to be taken into account in the shape of macrostructures, there is more design scope.

[0087] The disclosure is not limited to the embodiments discussed above. All the features described in the description or features claimed in the claims or features shown in the drawings can be combined with one another within the scope of this disclosure.

Claims

1. An at least partial endoprosthesis, in particular for the human knee, wherein the at least partial endoprosthesis is designed such that the sagittal cut, which is required in particular for corresponding implantation, deviates decentrally in the anterior region, and/or wherein an anterior region of the at least partial endoprosthesis, which in particular faces the anterior region of the corresponding tibia after insertion of the at least partial endoprosthesis into the human body, has an inclined surface.

2. The at least partial endoprosthesis according to claim 1, wherein the inclination of the inclined surface is between 20 degrees and 70 degrees, preferably between 25 degrees and 65 degrees, particularly preferably between 30 degrees and 60 degrees, very particularly preferably between 35 degrees and 55 degrees, in particular with respect to the tibia.

3. The at least partial endoprosthesis according to claim 1 or 2, wherein the at least partial endoprosthesis has a gradual transition, in particular between a sagittal surface and a horizontal surface of the at least partial endoprosthesis.

4. The at least partial endoprosthesis according to claim 3, wherein the gradual transition has a radius.

5. The at least partial endoprosthesis according to any of claims 1 to 4, wherein the at least partial endoprosthesis has or is a bicompartmental endoprosthesis.

6. An endoprostheses system, wherein the endoprosthesis system has at least two at least partial endoprostheses according to any of claims 1 to 5.

7. The endoprostheses system according to claim 6, wherein the endoprosthesis system is used in connection with a bicondylar femur.

8. An endoprosthesis (54), wherein at least a portion of a sunace of the endoprosthesis (54) facing the corresponding bone (55) and/or joint part has a macrostructure (53) for ensuring the primary stability of the endoprosthesis (54).

9. The endoprosthesis (54) according to claim 8, wherein the surface facing the corresponding bone (55) and/or the joint part has the macrostructure (53) completely or extensively.

10. The endoprosthesis (54) according to claim 8 or 9, wherein the macrostructure has honeycomb structures, in particular honeycomb-shaped ribs (40), and/or wave-shaped structures, in particular wave-shaped ribs, and/or zigzag structures, in particular zigzag ribs, and/or tire tread-like structures, in particular tire tread-like ribs.

11. The endoprosthesis (54) according to any of claims 8 to 10, wherein the macrostructure (53) has a plurality of spines and/or pins and/or spikes.

12. The endoprosthesis (54) according to claim 11, wherein at least some, preferably each, of the spines and/or pins and/or spikes has a length between 4 mm and 8 mm, preferably between 5 mm and 7 mm, particularly preferably between 5.5 mm and 6.5 mm, very particularly preferably of approximately 6 mm.

13. The endoprosthesis (54) according to claim 11 or 12, wherein at least some, preferably each, of the spines and/or pins and/or spikes has a diameter between 0.5 mm and 2.5 mm, preferably between 1 mm and 2 mm, particularly preferably between 1.3 mm and 1.7 mm, very particularly preferably of approximately 1.5 mm.

14. The endoprosthesis (54) according to any of claims 8 to 13, wherein the corresponding structures of the macrostructure (53) are designed to be larger and/or deeper in regions in which greater loads and/or a lower bone quality are to be expected with respect to the corresponding bone (55) and/or joint part.

15. The endoprosthesis (54) according to any of claims 8 to 14, wherein the endoprosthesis (54) nas or consists of a flexible material, preferably flexible thin material, particularly preferably polyethylene, very particularly preferably polyethylene having a thickness of between 1.5 mm and 2.5 mm, and/or biomaterial.

16. The endoprosthesis (54) according to any of claims 8 to 15, wherein the endoprosthesis (54) has or consists of plastics material, in particular polyether ether ketone (PEEK) and/or polyaryletherketone (PAEK) and/or polyethylene (PE) and/or ultra-high molecular weight polyethylene (UHMWPE) and/or UHMWPE mixed with Vitamin E, and/or hydrogel, and/or artificial cartilage and/or human cartilage.

17. An intraoperatively adjustable endoprosthesis, wherein the intraoperatively adjustable endoprosthesis has a basic form, wherein the basic form can be adjusted intraoperatively on the basis of shape data corresponding to the anatomical conditions of the respective patient.

18. The intraoperatively adjustable endoprosthesis according to claim 17, wherein the shape data are obtained intraoperatively, in particular by means of computer tomography and/or magnetic resonance tomography and/or endoscopy and/or sonography and/or 3D scans, preferably light-based and/or laser-based 3D scans.

19. The intraoperatively adjustable endoprosthesis according to claim 17 or 18, wherein the basic form is adapted by milling, in particular CNC milling, and/or laser cutting and/or waterjet cutting.

20. The intraoperatively adjustable endoprosthesis according to any of claims 17 to 19, wherein the intraoperatively adjustable endoprosthesis and/or the basic form has or consists of artificial cartilage and/or human cartilage.

21. An endoprosthesis (61), wherein the endoprosthesis (61) has at least one structure (62) for ensuring the primary stability of the endoprosthesis (61), wherein the at least one structure (62) at least partially has or consists of a material that can be reabsorbed by the human body.

22. The endoprosthesis (61) according to claim 21, wherein the at least one structure (ozj completely has or consists of the material that can be resorbed by the human body.

23. The endoprosthesis (61) according to claim 21 or 22, wherein the at least one structure (62) has at least one anchoring pin, in particular at least one peg, and/or at least one fin.

24. The endoprosthesis (61) according to any of claims 21 to 23, wherein the material that can be resorbed by the human body has or is magnesium and/or polylactide (PLLA) and/or poly(lactic-co-glycolic acid) (PLGA).

25. The endoprosthesis (61) according to any of claims 21 to 24, wherein at least a portion of a surface facing the corresponding bone and/or joint part, preferably the surface facing the corresponding bone and/or joint part, of the endoprosthesis (61), is designed to enable or facilitate the corresponding bone and/or joint part to grow.

26. The endoprosthesis (61) according to any of claims 1 to 5 or 8 to 25, wherein at least the portion of the surface facing the corresponding bone and/or joint part, preferably the surface facing the corresponding bone and/or joint part, of the endoprosthesis (61), has titanium and/or titanium particles.